Why is my Mystery Snail Shell Cracked? (With 5 Solutions)

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Since mystery snails are relatively easy to grow, I enjoy keeping them in my aquarium. However, once in a while, I notice things that disturb me. For instance, I noticed that the shell of my mystery snail was cracked quite a few times. Over the years, I learned a few reasons for the problem, and in most cases, I was even able to heal my snail. Now, I am willing to share my experience.

Mystery snails typically crack their shells due to direct trauma, such as tankmates attacks and collisions. However, cracks also occur due to low water quality, including acidic conditions and low calcium levels. In some cases, snails crack their shell when their growth is too accelerated.

As we proceed, I will list a few other reasons that may crack your snail’s shell, including the case in which the crack is actually an illusion. Ultimately, I will show you how to treat snails that cracked their shell and in which cases spontaneous healing is not likely to occur.

Why is my Mystery Snail Shell Cracked?

A mystery snail is born with its shell, which is essential to the snail’s life as any other organ. For that reason, any cracks you see in your snail’s shell should concern you. Mystery snail shells can crack for any number of reasons, including:

1. Attacks From Other Tankmates

Mystery snails are docile, peaceful creatures. They are non-aggressive. However, that won’t stop the other creatures in their tank from attacking them. Other snails may nibble on your mystery snail’s shell. 

But if it takes a severe hit from a fish, that might be enough to crack its shell. This is why you have to be careful whenever you select tankmates for your mystery snails. You can’t exactly trust them to defend themselves.

2. Poor Conditions in the Store

Some snails have shells that were cracked before you bought them. Not all stores can be trusted to look after their snails. Some stores keep their mystery snails in the worst possible conditions. They not only place them in tanks with the wrong fish, but they do not bother to maintain the right parameters in their water.

As a result, their shells deteriorate to the point where they finally break. However, if you are new to snails, it might not occur to you to carefully investigate your snail before you buy it. For that reason, you are just as likely to take home a snail with a cracked shell.

3. Accidents and Injuries

Mystery snails encounter accidents all the time that are more than capable of cracking their shells. For instance, they have been known to leave their aquariums. If you leave space in the lid, they will use it to escape. And once they leave the tank, anything can happen to them.[1]

They may fall from a great height because they stayed out for so long that they started to dry out. Someone can also step on them. Even if they stay in the tank, they can get stuck in the filter intake slots. And in your attempt to remove them, you may injure them, especially if their body has swollen because of the stress.

4. The Cracks are Actually Illusions

Some cracks are not actual cracks but, rather, illusions. Some mystery snails have rough shells with lines that may look like cracks from certain angles. But if your snail is new to the tank, as it matures, and if the conditions in the tank are ideal, the creature’s shell will become smoother and clearer. 

At this point, you will find that the lines that looked like cracks are no longer prominent. Even if these lines persist, they are not a threat. Regardless, make sure you have a real crack on your hands before you panic. 

Take the snail out of the water where possible so that you can take a closer look at the shell. Touch the crack with your fingers. In some cases, you may be surprised to find that it is merely a trick of the light.

5. The Water is Too Soft or Acidic

Mystery snails require hard water to thrive. If the water is too soft and acidic, it will cause the shell to dissolve. Mystery snails in too soft water are just as likely to develop holes in their shells.[2] While cracks are a problem, holes are far worse. They are a more significant threat to the snail’s life

6. Lack of Calcium

Snails require a diet that has sufficient quantities of calcium, especially when they are young. Snails that do not have enough calcium will develop thin shells that are either already cracked or more likely to crack down the line.[3]

Some aquarists have theorized that some snails consume so much calcium that the excessive deposits on the shell produce uneven growth, leading to cracks.[4] However, it is a more common belief that low calcium concentrations are to blame.

7. Bad Genetics and Accelerated Growth

Snails are born with their shells. And as was noted before, the shells are just as crucial to the mystery snail as any other organ. For that reason, it is more than possible for a genetic defect to result in a cracked shell.

Some snails have the disadvantage of growing so fast that their bodies do not have the time to build strong shells. The weak shells that are inevitably produced eventually crack. You typically see that in snails that grow larger each week.

How to Treat Mystery Snails With a Cracked Shell?

Because the shell is vital to the snail’s health, you must take steps to treat it whenever it cracks. Some practical solutions include:

1. Patching the Crack

Believe it or not, you can patch a crack in a shell the same way you would patch a crack in a wall. The key is to use the right plaster. Some people place glue over the crack, but that is dangerous. If the glue touches the flesh beneath the shell, the snail will suffer.

For the best results, you should find an object that you can place over the crack. A piece of another’s snail’s shell will do. The same goes for an eggshell, gauze, a piece of plastic, anything that can cover the crack.

Once your plaster of choice has been applied, you can add nail varnish after it has dried. There is no standard method for patching a cracked shell. You can experiment with various techniques and tools.

2. Improving the Tank’s Conditions

For your snail to heal, it requires the best possible conditions in the tank. That means a pH of 7.5 to 8.5, a temperature of 68 to 82 degrees F, and a tank of at least 10 gallons.[5] Don’t forget to raise the hardness of the water.

You should also pay close attention to the pH. As you now know, acidic water with a low pH can cause a mystery snail’s shell to deteriorate. You can solve this problem by raising the pH. A teaspoon of baking soda (for ten gallons of water) can achieve this objective.[6]

I would also suggest that you get yourself a kit that could measure the pH, ammonia, nitrates, and nitrites in your tank. Personally, I use the API Aquarium Test Kit (link to Amazon). That affordable bundle measures the desired parameters within minutes and lasts for hundreds of tests.

Water changes are crucial to the health of a mystery snail. They will keep the tank clean and reduce the concentration of toxins like ammonia and nitrites. Start with 15-20% weekly changes and see how your tank reacts.

If your heater doesn’t work correctly, you must get a better one. Temperature fluctuations will slow the recovery of your mystery snail and stress your entire community tank. After testing multiple devices, the only heater that answers my needs is the Cobalt Aquatics Neo-Therm Pro Aquarium Heater (link to Amazon). I also reviewed it here.

3. Enriching Your Tank with Calcium and Minerals

Keep a calcium test kit on hand. Snails need calcium to maintain the health of their shells. Many aquarists use cuttlebone to increase the levels of calcium in their mystery snail tank. If you have never heard of cuttlebone, go to a fish store and ask for some calcium supplements.

Another option is the JOR Tourmaline Balls (link to Amazon). These act as an aquarium supplement and will enrich your water with calcium while efficiently balancing the pH. Other creatures, such as Bettas, Crayfish, and shrimp, will also benefit from those.

4. Feeding the Mystery Snail Properly

While the calcium content in the water is essential, snails also require calcium in their diet. This is why aquarists feed their mystery snails blanched kale and cucumbers. These creatures will eat the algae in your tank. 

However, you are still encouraged to supplement their diet. You can use everything from pellets and flakes to algae wafers, leaf lettuce, and zucchini squash. The more you enrich their diet, the more it is likely that their shell will recover.

5. Picking the Right Tankmates

Mystery snails are relatively peaceful. They shouldn’t live in tanks with large fish like cichlids that are more likely to cause them harm. They should be kept with suitable tankmates such as guppies, shrimp, and corydoras that will coexist peacefully with them.

Will a Snail Die if its Shell is Cracked?

Snails are likely to die if their shell is severely cracked. A severe break in the shell is a danger to the snail because the creature is at risk of drying out. However, if the shell is cracked but is still relatively intact, the snail will survive, especially if treated properly.

In other words, it depends. Snails rely on their shells. A mystery snail cannot live outside its shell, and any snail that is separated from its shell will ultimately die. That is to say, the health of the shell affects the health of the snail.

If the break in the shell is so severe that it has mangled the snail’s body on the inside, your only option is to euthanize the snail. Snails whose shells have been broken beyond repair die slowly. It can take them hours to dry out.

Can Mystery Snails Repair Their Shells?

Mystery snails can eventually repair their shells if the crack or hole is relatively small. It is possible to aid the process by adding oyster shells, crushed coral gravel, and cuttlebones to raise the hardness. However, severe injuries are not likely to heal, mostly if an infection has spread.

So if the conditions are ideal and the snail doesn’t suffer any additional injuries, the cracks will mend. But the same cannot be said for situations where the snail suffers a severe break that exposes its organs.

A large break puts the snail at risk of drying out. This is why aquarists that are treating snails with severe breaks start by placing them in humid conditions. The objective is to keep them from drying while they patch the break.

As was mentioned, infections are another concern, so aquarists also use Melafix to treat tanks with injured snails. They want to protect the snail from diseases before they apply the patch.

You should know that, while shells can heal, they do not always return to their former state. Some mystery snails that were injured in the past have shells that will always look cracked. But if their insides are no longer exposed, they shouldn’t concern you. Though, you can still patch those cracks if you want.


In most cases, your mystery snail has cracked its shell due to direct trauma. That could be a collision inside the tank or attacks from aggressive tankmates. In some cases, snails escape their aquarium and crack the shell outside. Either way, it requires your attention.

You can treat the crack by applying a patch. However, it is also worth checking the water parameters. Ensure that the temperature and pH are ideal for mystery snails so that the healing process will improve. It would also be a good idea to remove tankmates that consistently harass your snail.


  1. https://www.aquariumcarebasics.com/freshwater-snails/mystery-snail/
  2. http://www.fishpondinfo.com/snails/snailhealth.htm
  3. https://www.welcomewildlife.com/all-about-land-snails/
  4. https://www.petsnails.co.uk/problems/bad-shell-growth.html#start
  5. https://fishtankadvisor.com/mystery-snail/
  6. https://aquariawise.com/mystery-snails-guide/